Spatial Selection of Features within Perceived and Remembered Objects

Abstract

Our representation of the visual world can be modulated by spatially specific attentional biases that depend flexibly on task goals. We compared searching for task-relevant features in perceived versus remembered objects. When searching perceptual input, selected task-relevant and suppressed task-irrelevant features elicited contrasting spatiotopic ERP effects, despite them being perceptually identical. This was also true when participants searched a memory array, suggesting that memory had retained the spatial organization of the original perceptual input and that this representation could be modulated in a spatially specific fashion. However, task-relevant selection and task-irrelevant suppression effects were of the opposite polarity when searching remembered compared to perceived objects. We suggest that this surprising result stems from the nature of feature- and object-based representations when stored in visual short-term memory. When stored, features are integrated into objects, meaning that the spatially specific selection mechanisms must operate upon objects rather than specific feature-level representations.

Note:
Funding Information: D.E.A. is supported by a post-doctoral fellowship from the Economic and Social Research Council, UK. D.E.A. and G.S. are supported by a project grant from the John Fell fund (Oxford University Press). G.S. and A.C.N. are both supported by project grants from the Wellcome Trust. B-C.K. was supported by a Scholarship from the National Science Council of Taiwan.

Declaration of Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Ethics Approval Statement: Each participant provided written informed consent. The study was approved by the medical ethics review board at the University of Oxford, UK.

Keywords: ERPs; electrophysiology; spatial attention; task-set control; visual short-term memory; working memory